1. Field of Invention
The invention belongs to the technical art of a wiper apparatus incorporated in vehicles, such as automobiles, buses, trucks, etc.
2. Description of Related Art
Generally, in this type of wiper apparatus, a parallel wiping type wiper apparatus is known, which is structured so that a pair of pivot axes are provided approximately parallel to each other at a roughly central part and one side in the left and right direction of a window surface, respective wiper arms attached to the pivot axes are reciprocated and are caused to swing in the upper and lower reciprocatory range on the window surface to wipe off the window surface. In such a type of wiper apparatus, there is a type structured such that the two pivot axes are rotated clockwise and counterclockwise by one drive motor, wherein a link mechanism is provided with a link rod that advances and retreats upon receiving the rotating drive power of a wiper motor, and first and second link arms that swing upon receiving advancement and retreating movement of the corresponding link rod, the corresponding link mechanism is connected to the wiper motor, and the respective pivot axes are integrally linked to the respective swinging first and second link arms. Thereby, the respective pivot axes are rotated clockwise and counterclockwise.
However, in a case where the above-described parallel wiping type wipers are attached to a window surface of a vehicle, because the window surface is generally formed so as to be curved in the left and right direction, and because the respective pivot axes are attached normal to the tangential line of the window surface portion of the vehicle, the pivot axis attached at one side faces outwardly in the left or right direction with respect to the curved surface of the window, and is caused to protrude for an axial slip with respect to the pivot axis for the central portion.
However, in such a case, as shown in FIG. 6, because the axial slip occurs between the axial center line S1 of the pivot axis 2 for the central portion and the axial center line S2 of another pivot axis 3 for one side, the link surfaces (planes including the reciprocating swinging locus) of the first and second link arms 11, 13, which are connected roughly orthogonally to the respective pivot axes 2 and 3, are not parallel to each other, wherein the swinging direction thereof accordingly slips. Therefore, as shown in FIG. 7, a so-called rod rush angle between the second link rod 12 and the first and second link arms 11, 13 may be increased. Ideally, it is preferable that the rod rush angle be zero (wherein the axial line in the longitudinal direction of the second link rod 12 and the plane including the reciprocatory swinging locus of the respective first and second link arms 11 and 13 become parallel to each other). Therefore, if the rod rush angle is increased and exceeds a predetermined angular range, abnormal noise is generated between the second link rod 12 and the first and second link arms 11, 13, and inefficient power transmission may result. In addition, there is a fear that the second link arm 12 will fold or bend or that the second link rod 12 will come out of, or disengage from, the respective link arms 11, 13. The theme of the invention resides therein.
The invention was developed in view of the above-described situations in order to solve the problems. It is therefore an object of the invention to provide a wiper apparatus comprising a pair of pivot axes, one of which is disposed at the lower, roughly central portion in the left and right direction of a curved window surface of a vehicle so as to protrude therefrom, and the other of which is disposed at the lower, one side portion of the curved window surface of a vehicle so as to protrude therefrom; a pair of link arms, each secured at the lower end of the respective pivot axes; a link rod for connecting the respective link arms; and a wiper motor coupled to and interlocked with the link rod; in which wiper arms, each disposed at the tip ends of the pivot axes, are structured so that the wiper arms are caused to wipe off the window surface through reciprocation on the basis of reciprocatory swinging of the respective link arms resulting from drive and rotation of the wiper motor; wherein a surface including a reciprocatory swing locus of at least one link arm is disposed so as to become parallel to the axial line in the lengthwise direction of the link rod.
As a result, the rod rush angle, that is formed by the link arm and link rod, can be decreased.
In such a type of wiper apparatus, surfaces in the forward and backward direction, including the axial centerlines of the respective pivot axes according to the invention, are disposed so as to become roughly parallel to each other.
In addition, surfaces in the left and right direction, including the axial centerlines of the respective pivot axes according to the invention, are disposed so as to become roughly parallel to each other.
Also, the protruding end portion of one pivot axis according to the invention is inclined for positional slip in the forward and backward direction with respect to the protrusion end portion of the other pivot axis.
Further, the wiper arms according to the invention are provided with a wiper blade at the tip ends thereof in a state where the wiper blade is pressed to the window surface of the vehicle, and the pressing direction of the wiper blade is established so as to be inclined with respect to the axial center line of the pivot axes so that the direction becomes roughly orthogonal to the window surface.